Conventionally, secret data is kept in a security apparatus which prevents it from being illegally obtained by a third party, and is processed inside the security apparatus. However, the unauthorized third party attempts to illegally obtain the secret data by using various units and methods. For instance, the unauthorized third party tries accessing the security apparatus to obtain indirect data with little security which indirectly relates to the secret data, and obtains the secret data by systematically using the indirect data. Thus there is a conventional demand for units and methods which can effectively prevent an unauthorized third party from illegally obtaining secret data.
Japanese Patent Application Laid-Open Nos. 8-44805 and 63-123184 disclose technology relating to a security apparatus which counts the number of time secret data is accessed by using a counter, and deletes the secret data when the access number has exceeded a threshold, thereby preventing an unauthorized third party from illegally obtaining the secret data.
Furthermore, conventionally, as a method of maintaining security, there is a method of requesting input of a code number when executing a predetermined process, and restricting the process when the validation result of the code number has exceeded a threshold.
Nevertheless, in conventional security apparatuses such as that described above, when the interface with outside apparatuses becomes clear, it becomes possible to frequently execute processing to obtain indirect information relating to the secret information. Accordingly, conventionally, illegally obtaining of the secret data is prevented by deleting the secret data, based on a comparison result between the counter result (number of accesses) of the counter and a threshold.
However, in conventional security apparatuses, there are cases in which the unauthorized third party can clear the counter result before it reaches the threshold, as a result of a breakdown in the interface and the like. In this case, since the indirect information is obtained without restrictions, there is a problem that illegally obtaining of secret information is easily tolerated.
Therefore, it is an object of the present invention to provide a security apparatus capable of increasing security relating to illegally obtaining of secret data, and to a computer-readable recording medium which security programs are stored in.